Administering an injection is a process which presents a number of risks and challenges for users and healthcare professionals, both mental and physical. Medicament delivery devices typically fall into two categories—manual devices and autoinjectors. In a conventional manual device, manual force is required to drive a medicament through a needle. This is typically done by some form of button/plunger that has to be continuously pressed during the injection. There are numerous disadvantages associated with this approach. For example, if the button/plunger is released prematurely, the injection will stop and may not deliver an intended dose. Further, the force required to push the button/plunger may be too high (e.g., if the user is elderly or a child). And, aligning the medicament delivery device, administering the injection and keeping the medicament delivery device still during the injection may require dexterity which some patients (e.g., elderly patients, children, arthritic patients, etc.) may not have.
Autoinjector devices aim to make self-injection easier for patients. A conventional autoinjector may provide the force for administering the injection by a spring, and trigger button or other mechanism may be used to activate the injection. Autoinjectors may be single-use or reusable devices.
Usually the injection needle is equipped with a protective needle sheath for keeping the needle sterile and preventing it from being mechanically damaged. The protective needle sheath is attached to the needle when the auto-injector or the medicament container is assembled. In order to prepare for an injection, the protective needle sheath must be removed, which may expose a user to a high risk of needle stick injuries.
There remains a need for an improved sheath removal mechanism.